Prashant V. Kamat

Bio: Prashant V. Kamat is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Racism & Excited state. The author has an hindex of 140, co-authored 725 publications receiving 79259 citations. Previous affiliations of Prashant V. Kamat include Indian Institute of Technology Kanpur & Council of Scientific and Industrial Research.

Photoelectrochemical Behavior of Bi2S3 Nanoclusters and Nanostructured Thin Films

Abstract: Quantized semiconductor nanoclusters of Bi2S3 are prepared in acetonitrile by reacting BiI3 with H2S or Na2S. Both preparation methods yield stable colloids with particle diameters of ≤5 nm. Excitation with a 355-nm laser pulse results in transient bleaching in the 400−500-nm region. This process is followed by the formation of S-surf with a difference absorption maximum around 540 nm. This we attribute to the chemical changes associated with the hole-trapping process. A composite thin film electrode comprised of SnO2/Bi2S3 nanocrystallites has been prepared by sequential deposition of SnO2 and Bi2S3 films onto an optically transparent electrode, and its photoelectrochemical behavior has been studied. The thin film is photoactive in the visible and near-IR and exhibits an incident photon to photocurrent efficiency (IPCE) of ∼15% at 400 nm.

Photoelectrochemistry in particulate systems. 6. Electron-transfer reactions of small cadmium sulfide colloids in acetonitrile

Abstract: Small colloidal CdS particles (particle diameter < 25-42 A) have been prepared in acetonitrile and their absorption and emission properties characterized. A transient bleaching was observed when CdS colloids were subjected to bandgap excitation with a 355-nm laser pulse. The recovery of the bleaching which consisted of at least two components has been attributed to the recombination of trapped charge carriers and to the process of anodic corrosion. The red emission of CdS colloid can be quenched with an electron scavenger such as methylene blue. The quantum yield for the reduction of oxazine and thiazine dyes varied from 0.04 to 0.08 and was dependent on the reduction potential of the dye. The electron-transfer reactions of CdS colloids have been investigated by using nanosecond laser flash photolysis and microwave absorption techniques.

Role of reduction in the photocatalytic degradation of TNT

Abstract: The reduction of TNT by electrochemical and photoelectrochemical techniques has been investigated to obtain insight into the role of reductive transformations in a photocatalytic degradation process. TNT was observed to be labile to reductive transformation by a platinum electrode at electrochemical potentials commensurate with the flat band potential of TiO2, and aminodinitrotoluene species were detected as early reduction products. Oxygen did not influence the rate of reductive TNT transformation, but byproducts were more stable in aerated than deaerated conditions. Photocatalytic reduction of TNT was analyzed using CdS as a chromophore coupled to TiO2 and visible light excitation so that direct photolysis of TNT was precluded. Under deaerated conditions, reduction of TNT occurred through both direct and sensitized mechanisms, predominantly forming aminodinitrotoluene compounds as relatively stable byproducts. Photocatalytic transformation and mineralization of TNT was also examined with particulate fil...

Light energy conversion using mixed molecular nanoclusters. Porphyrin and C60 cluster films for efficient photocurrent generation

Abstract: Composite molecular nanoclusters of fullerene and porphyrin prepared in acetonitrile/toluene mixed solvent absorb light over the entire spectrum of visible light. Upon slow evaporation of the solvent on the copper grid, these mixed nanoclusters undergo close-packed stacking to produce either tubular- or square-shaped microcrystallites and differ from those obtained from single-component clusters. The highly colored composite clusters can be assembled as 3-dimensional arrays onto nanostructured SnO2 films using an electrophoretic deposition approach. The composite cluster films exhibit an incident photon-to-photocurrent efficiency (IPCE) as high as 17% at an applied potential of 0.2 V vs SCE, which is significantly higher than the additive effect observed from either porphyrin (IPCE = 1.6%) or fullerene clusters (IPCE = 5.0%) under similar photoelectrochemical conditions. The high IPCE values observed with porphyrin and C60 clusters demonstrate the synergy of these systems toward yielding efficient photoin...

Electron Transfer Cascade by Organic/Inorganic Ternary Composites of Porphyrin, Zinc Oxide Nanoparticles, and Reduced Graphene Oxide on a Tin Oxide Electrode that Exhibits Efficient Photocurrent Generation

Abstract: A bottom-up strategy has been developed to construct a multiple electron transfer system composed of organic/inorganic ternary composites (porphyrin, zinc oxide nanoparticles, reduced graphene oxide) on a semiconducting electrode without impairing the respective donor–acceptor components. The hierarchical electron transfer cascade system exhibited remarkably high photocurrent generation with an incident-photon-to-current efficiency of up to ca. 70%.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells

Abstract: Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.